How to fix the seat of this chair?

I would just create a new cushion .for it

I agree. Remove the caning. Cut a plywood panel slightly larger than the hole and upholster it. Then screw it on from underneath

Repairing Grandma’s Chair: The Lost Art of Caning

https://www.lancasterfarming.com/farm_life/antiques_and_history/repairing-grandma-s-chair-the-lost-art-of-caning/article_f6453004-797d-507e-b1d5-d25f5cbfe612.html

You could absolutely make a new cushion and attach it up through the bottom with short screws. But you could also recane it, here's a youtube video on how to do that: https://www.youtube.com/watch?v=Gi0Gt9RU0Ro

https://www.amazon.com/cane-chair-repair-kit/s?k=cane+chair+repair+kit

That should do it.

you can replace it with caning or even wood, fabric , etc here is info for you

https://www.youtube.com/watch?v=A5IRBuwONnA

I would remove all the wicker and replace when leather and nail it in

Hello there,

You can buy this Cane Seating by the metre from a craft shop. You can also buy a book to help you do it or ask the assistant for help on how!

I wouldn't bother recaning it. It would be a ton of work and when you can make it look nice in another way that is a lot easier, I wouldn't bother. I love re-upholstering and the way I would handle this one would be to use some leather instead of the caning. You would staple into the groove and hide the staples with a trim or upholstery nails. I can't tell what that groove looks like though from the picture so you will have to see how that would work.

The other idea is creating a plywood shape that sits on top that you can upholster and screw into the seat of the chair. This way you can have a built in cushion.

Just throwing alternative ideas out there besides re-caning. If you like the idea of caning than go for it! The chair will look just as nice though either way so it is up to you! Good luck!

Here's a post that might help - https://www.youtube.com/watch?v=XiMLol7vJos

You can purchase replacement cane for it or take it to a pro to have it replaced.

You can either replace the caning or do an alternative method. It would depend on your preference. Since this is a child's chair, I would not replace it with caning, caning does not matter to a child.

I would remove the existing caning and replace it worth a piece of plywood fit to the chair-nail it in. Then add a comfortable cushion attached (tied) to the the outer posts of the chair back.

Here is a site for instruction on re-caining https://www.wickerwoman.com/articles/chair-caning-instructions

https://seatweaving.org/store/how-to-cane-chairs.html

It is not an easy job, you may want to just add a piece of wood and make a cushion

I would start from scratch and make and make a new one